Dietary monounsaturated fatty acids enhance cholesterol efflux from human fibroblasts. Relation to fluidity, phospholipid fatty acid composition, overall composition, and size of HDL3.

This study was designed to determine whether modifications induced by dietary fats on the high-density lipoprotein3 (HDL3) physicochemical characteristics could affect cholesterol efflux and intracellular cholesterol content, leading to upregulation of low-density lipoprotein (LDL) receptor activity from cultured fibroblasts. Serum HDL3S were obtained from 12 healthy women aged 26 to 49 years who adhered to four 7-week isocaloric diets containing 30% of the caloric intake as fat. Of the total calories, 15.6% of each diet was provided by (1) milk fats, rich in saturated fatty acids; (2) sunflower oil, rich in n-6 polyunsaturated fatty acids; (3) olive oil, rich in monounsaturated fatty acids; and (4) rapeseed oil, rich in n-3 polyunsaturated fatty acids. HDL3 isolated after the monounsaturated fatty acid diet induced the greatest cellular [3H]free cholesterol efflux, reduced the content of intracellular cholesterol, and enhanced 125I-LDL degradation. Univariate regression analyses suggested that the increased capacity of HDL3 to promote cellular [3H]free cholesterol efflux was in part due to its greater fluidity, higher cholesteryl ester content, elevated linoleic to linolenic acid ratio in phospholipids, and its smaller size. In conclusion dietary fats induced physicochemical changes in HDL3, which strongly modulated cellular cholesterol homeostasis in vitro. These data also suggest a novel mechanism by which dietary fats exert their effect on atherosclerosis.

Effects of dietary fats on the fluidity of human high-density lipoprotein: influence of the overall composition and phospholipid fatty acids.

The present study was undertaken to analyze whether the changes induced by dietary manipulations in the chemical composition of HDL, particularly in total phospholipids, phosphatidylcholine and sphingomyelin fatty acid composition, modified their fluidity. 12 healthy women, aged 26-49 years were studied. They consumed, over periods of 5 weeks, various isocaloric diets, each containing 30% of the calories as fat. 15.6% of the total calories were provided successively by olive oil, soybean oil, corn oil, and milk fats. The HDL fluorescence anisotropy was measured with 1,6-diphenyl-1,3,5-hexatriene (DPH) by fluorescence polarization. The HDL from the monounsaturated diet, olive oil, were the most fluid particles. The HDL fluorescence anisotropy was positively correlated with their free cholesterol percentage and negatively correlated with their triacylglycerol content and their triacylglycerol/phospholipid ratio. Moreover, the HDL fluorescence anisotropy was negatively correlated with the percentage of oleic acid in their total phospholipids and particularly in the phosphatidylcholine. These results suggest that the percentages of triacylglycerol and oleic acid in phospholipids of HDL have a fluidifying effect on these lipoproteins.

[Antiheparin immunoglobulin in malignant lymphoma with hypertriglyceridemia, in the hamster]. / Une immunoglobuline anti-héparine chez le hamster hypertriglycéridémique porteur d'un lymphome malin

A massive hypertriglyceridemia associated with low post heparin lipolytic activity, was demonstrated during the growth of a transplanted lymphoma in Hamsters. An immunoglobulin, with high anti-heparin activity, was extracted from the tumor. It could inhibit both the anti-thrombin and prolipase activity of heparin. The role of this anti-heparin immunoglobulin in triglyceride metabolism allows us to consider the hypertriglyceridemia of lymphoma-bearing Hamsters as one of the two previously described types of auto-immune hyperlipidemia.

[Hyperlipemia and tumors : post heparin lipase activity of the hamster bearing a malignant lymphoma]. / Hyperlipidémie et tumeurs : l'activité lipasique post-héparine du hamster porteur de lymphome malin

Subcutaneous transplantation of Greene lymphoma in golden hamsters is followed by a type IV-V hyperlipoproteinemia with major hupertriglyceridemia and impairment of labelled triglyceride clearance. Postheparin lipase activity studies show that this hyperlipidemia is correlated with the decrease in the lipolytic enzyme, which plays an important role in triglyceride clearance. The role of the tumor is considered.